#include <iostream>
using namespace std;
double &f ();

double valor = 10.0;

int main () {

	double nuevo_valor;
	cout << f() << endl;
	nuevo_valor = f();
	cout << nuevo_valor << endl;

	f() = 7.5;
	cout << f() << endl;

	return 0;
}

double &f () { return valor; }
